1. Field of the Invention
This present invention relates to a sub-roofing element for a flat, plate-shaped structural element, in particular for a solar energy collection module that can be fastened to joist elements that can be laid on a pitched roof in the ridge-eaves direction, whereby the sub-roofing element is made of watertight material and has at least one water channel.
2. Background Information
Such a system is described in German Patent No. 94 09 453.9 U1, for example. In this system, modules are arranged so that they overlap one another in the longitudinal direction of the roof. In this specification, the longitudinal direction is called the ridge-eaves line, and the transverse direction is designated a line parallel to the ridge or to the eaves. As the joist elements, there are wooden profiles laid in the edge-eaves direction which, on their ridge-side end, are in contact with a roof batten and on their eaves-side end are in contact with a wooden batten that is laid parallel to a roof batten and adjacent to the latter. The wooden batten projects beyond the upper edge of the roof batten by approximately the thickness of the module.
The wooden profiles, on their surface, have a depression that runs in the longitudinal center, so that this depression, when located on the edges of two modules butted against one another, serves as a drain channel for the discharge of any water that may have penetrated into the gap. Some of the disadvantages of this system are that additional wooden battens must be laid parallel to the roof battens, and that additional stays that are engaged around the eaves-side edge of the modules are necessary for fastening.
European Patent No. 0 547 285 and German Patent No. 33 14 637 disclose a roofing plate that can be provided on its upper side with a small-format module. The roofing plate is provided on one longitudinal edge with a water channel or drip edge, and on the other longitudinal edge with a cover channel or water stop. The module is always supported on the roofing plate close to the water channel and the cover channel. When the roof is being laid, the roofing plates are laid in a course parallel to the eaves, whereby one roofing plate, with its cover channel, always overlaps the water channel of a neighboring roofing plate in the same course, so that no rain water can penetrate between the roofing plates.